GPS location data may be used to determine the location of a vehicle on a roadway and may be used to track the speed and direction of the vehicle. This data may be used in the vehicle's navigation system, among other applications. Locations of a plurality of vehicles on a roadway may be used to identify current or predict future travel characteristics along roadways. Examples of applications that use GPS in this way are Google™ Waze™ or Apple® Maps. With these applications, users may opt-in and share their GPS location with the application, and receive warnings such as traffic congestion on their driving routes.